Hi,

I need help. I have a bug (one of many...) in a trivial meta-interpreter for CLP(Q) which I just don't understand. The constraints become the mirror of what they should be.

9 4 Call: ppl_insert_constraint(-32821246,A>=2) ? 9 4 Exit: ppl_insert_constraint(-32821246,A>=2) ? 8 3 Exit: solve_constraints(A>=2,-32821246) ? 7 2 Exit: solve({A>=2},-32821246) ? 10 2 Call: check_constraints(-32821246) ? 11 3 Call: ppl_space_dimension(-32821246,_7710) ? 11 3 Exit: ppl_space_dimension(-32821246,1) ? 12 3 Call: ppl_check_empty(-32821246) ? 13 4 Call: ppl_check_empty(-32821246,1) ? 13 4 Fail: ppl_check_empty(-32821246,1) ? 12 3 Fail: ppl_check_empty(-32821246) ? 14 3 Call: write(1) ?

14 3 Exit: write(1) ? 1 15 3 Call: write(' * ') ?

15 3 Exit: write(' * ') ? * 16 3 Call: ppl_get_constraints(-32821246,_7684) ? 16 3 Exit: ppl_get_constraints(-32821246,[1*A>= -2]) ? 17 3 Call: write([1*A>= -2]) ?

17 3 Exit: write([1*A>= -2]) ? [1*A>= -2]

Note that on the 1st line the constraint A >= 2 is inserted. However, on the last line when it is printed we have A >= -2!

Another experiment: | ?- solve({A==B+2}). 2 * [-1*A+1*B==2] % [vertex(-2*B),line(-1*A+ -1*B)] A = A, B = B ? | ?- solve({A+B==C+D-A+2}). 4 * [-2*A+ -1*B+1*C+1*D==2] % [vertex(-2*D),line(-1*C+1*D),line(-1*B+ -1*D),line(-1*A+ -2*D)]

Note that all the variables are negated, regardless of where they occur - or equivalently, the constant term is negated.

This is one of several bugs, but I just cannot see what is causing it and would appreciate suggestions.

Also, as you can see from above, I have to use "==" for "=" which is not clp(q) syntax. Obviously, "=" -> "==" can be done in in the meta-interpreter, but it would be better if it was dealt with in the interface.

ciao, Pat